Island



No. 6l6,892. Patented Ian. 3, I899.

F. u. BUSHNELL. STEAM VALVE OPERATING MECHANISM.

(Applicafiion filed Mar. 8, 1898:) (In .llodel.)

Bed/2451487177623 A Attorney;

'NITED STATES FREDERIO N. BUSHNELL, OF PROVIDENCE, RHODE ISLAND.

STEAM-VALVE-OPERATING MECHANISM.

SPECIFICATION forming part of Letters Patent No. 616,892, dated January 3,1899.

Application filed Mar h 8, 1898. Serial No. 673,036. (No model.)

To aZZ whom it may concern.-

Be it known that I, FREDERIO N. BUSHNELL, of Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Steam Valve-Operating Mechanism; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

This invention relates to the mechanism for operating rotary valves in a steam-engine. It is fully explained and illustrated in this specification and the accompanying drawings.

Figure 1 represents an elevation of a portion of the cylinder of a steam-engine with the improvement attached to it and shown in vertical section on line 1 1, Fig. 2. shows an end elevation of a part of the steam chest with a side elevation of the mechanism.

The object of this invention is to make a mechanism for the purpose of closing the ro tary valve quickly and surely and in which the force that closes the valve shall press steadily on it with the same pressure until the valve is fully closed, which is not the case in those arrangements using vacuum-cylinders, in which the force grows weaker as the valve closes, making it liable to be prevented from closing perfectly if it does not move freely.

The construction is as follows:

I A represents the cylinder of the engine, and O the stem of the rotary valve. A casting D is bolted to the cylinder A to hold two cylinders, an upper one E and a lower one J, placed vertically in line with each other. A piston Ris fitted to slide in the two cylinders, and the upper one is provided with a stuffing-box n to surround the piston and make it steam-tight. The lower cylinder consists of an air-tight box F, inclosing a cylinder J, open at its upper end, and a pis ton-head b is fitted to slide close in the lower part of the cylinder, but has a certain amount of windage to between it and the sides of the cylinder for about three-fourths of its length down from the top.

The piston R has a rectangular opening N made in it midway of its length, so that the opening will come opposite the valve-stem 0,

Fig. 2

and an arm 13 is attached to the valve-stem, having a rounded head P on its outer end, fitted to work in the opening N in the piston. Blocks c are fitted to slide in the opening and are placed one above and the other below the head P and have their faces next to the head made concave to fit the circle of the head. Taper-keys d are placed between the blocks 0 and the ends of the openings to adjust the blocks and take up any lost motion between them and the head P. The upper cylinder E is connected by a pipe L with the steam-supply pipe beyond the main View S, that the desired uniform pressure in that cylinder may be maintained and not be made to vary by any change of pressure caused by the exhaust or otherwise.

In operation the valve 0 when turned to admit steam to the cylinder raises the piston R by the arm B, and the air in the lower cylinder J is transferred from the upper part of that cylinder to the lower part through the windage-space around the piston-head Z7 as it rises. When the point for cutting off the steam in the engine is reached and the valve 0 is released, (by mechanism not shown,) the pressure of steam in the upper cylinder E will force the piston R down suddenly, and the air below the piston-head b will escape quickly through the windage into the upper part of the cylinder until the piston-head 1) reaches the lower part of the cylinder,where it fits closely, when the air remaining below the head will have to escape by means of the small holes 6 e, which allows it to escape slowly and bring the piston-head to a stop without a shock, but with the full pressure of steam on its upper end in the cylinder E, insuringits reaching the bottom. I

The air-tight box F, inclosing the lower cylinder J, serves to assist in transferring the air from one end of the cylinder to the other and also to prevent the disagreeable noise caused by the escape of the air around the head I) at each stroke of the piston.

Having thus described my improvement-s, I claim as my invention and desire to secure by Letters Patent 1. In a valve-operatin g mechanism the com bination with a rotary valve,of two cylinders, a single piston fitted to work in both cylinders, a steam-tight stuffing-box around the piston in one of said cylinders, a pipe connecting one of said cylinders with the steam-supply pipe between the main valve and the boiler, achest or box inclosing the other of said cylinders, holes communicating between said cylinder and the chest outside, substantially as described.

2. In a valve-operating mechanism the combination with the rotary valve, of two cylinders, a single piston fitted to Work in both cylinders, a steam-tight stuffing-box around said piston in one of the cylinders, a pipe connecting one of the cylinders with the main supplypipe between the main valve and the boiler, with means for connecting said piston with the valve, substantially as described.

3. In a valve-operating mechanism the combination of two cylinders with one piston working in both cylinders, a rotary valve, an arm attached to the stem of said valve and having a head on its outer end fitted to Work in an opening in said piston, a sliding block meets head, and taper-keys to adjust said blocks and take up the lost motion between said head and the ends of the opening in the piston,with means for securing said keys to the piston, substantially as described.

In testimony whereof I have hereunto set my hand this 7th day of March, A. D. 1898.

FREDERIG N. BUSHNELL. In presence of- I-I. E. BARLoW, BENJ. ARNOLD. 

